Perfect Number in C

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Perfect Number in C
vinaykhatri

Vinay Khatri
Last updated on June 16, 2024

    Here in this program, we will write a code which checks whether the entered number is a Perfect number or not.

    What is a Perfect number?

    When a positive integer is equal to the sum of its all possible divisors except itself, is known as a perfect number. For example, 6 is a perfect number because the sum of its all divisors is equal to 6 Divisors of 6 are 1, 2, 3 exclude 6. Sum of 6 all divisors = 1+2+3 = 6

    Statements to use:

    • For loop
    • If statements
    • Else statement

    Steps:

    • First, we will ask the user to enter a positive integer
    • Then we start a loop from 1 to the half of the entered number
    • Inside the loop, we will check which number is the divisor of the entered number.
    • If the number is a divisor of the entered number, we will sum it.
    • At last, we will check whether the summing of all the divisors is equal to the entered number or not
    • If it is equal to the entered number, we will print It is a perfect number, is not we will print it is not a perfect number.

    Perfect Number in C

    #include<stdio.h>
    #include<conio.h>
    void main()
    {
    int num, sum=0,i;
    clrscr();
    printf("Enter a Positive Integer: ");
    scanf("%d",&num);
    if (num==1)
        {
        printf("It is not a Perfect number");
        }
    else
        {
        for(i=1;i<=num/2;i++)
        {
            if(num%i==0)
                sum+=i;
        }
        if(sum==num)
            printf("It is a perfect number");
        else
            printf("It is not a perfect number");
     }
    getch();
    }

    Output

    Enter a Positive Integer: 6
    
    It is a perfect number

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